1. Field of the Invention
The present invention relates to prevention and treatment of rheumatoid arthritis by administration of a human beta defensin.
2. Background
Among many other elements, key components of innate immunity are the antimicrobial peptides (AMPs) that individually show considerable selectivity, but collectively are able to rapidly kill a broad spectrum of bacteria, viruses and fungi. The biological significance of AMPs is emphasized by their ubiquitous distribution in nature and they are probably produced by all multicellular organisms. In humans the predominant AMPs are the defensins. The human defensins are small cationic peptides that can be divided into α- and β-defensins based on the topology of their three intramolecular cysteine disulphide bonds. The α-defensins can be further subdivided into those that were first isolated from neutrophil granules (HNP1-4) and those that are expressed by Paneth cells in the crypts of the small intestine (HD5 and HD6). The β-defensins are mainly produced by epithelial cells in various tissues and organs including the skin, trachea, gastrointestinal tract, urogenital system, kidneys, pancreas and mammary gland. The best characterized members of the β-defensin family are hBD1-3. However, using various bioinformatics tools almost 40 open reading frames encoding putative β-defensin homologues have been annotated in the human genome. Some of the human defensins are produced constitutively, whereas others are induced by proinflammatory cytokines or exogenous microbial products.
It has become increasingly clear that the human defensins in addition to their direct antimicrobial activity also have a wide range of immunomodulatory/alternative properties. These include the induction of various chemokines and cytokines, chemotactic and apoptotic activities, induction of prostaglandin, histamine and leukotriene release, inhibition of complement, stimulation of dendritic cell maturation through toll-like receptor signaling and stimulation of pathogen clearance by neutrophils. Furthermore, the human defensins also play a role in wound healing, proliferation of epithelial and fibroblast cells, angiogenesis and vasculogenesis.
There is increasing evidence that the human defensins play an important role in many infectious and inflammatory diseases. Overexpression of human defensins is often observed in inflamed and/or infected skin most likely because of local induction by microbial components or endogenous proinflammatory cytokines. In psoriasis hBD2 and hBD3 are overabundant and in lesional epithelium of patients with acne vulgaris or superficial folliculitis a significant upregulation of hBD2 has been observed. On the other hand, downregulation of hBD2 and hBD3 has been associated with atopic dermatitis.
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks the joints producing a inflammatory synovitis that often progresses to destruction of the articular cartilage and ankylosis of the joints. Rheumatoid arthritis can also produce diffuse inflammation in the lungs, pericardium, pleura, and sclera, and also nodular lesions, most common in subcutaneous tissue under the skin. Although the cause of rheumatoid arthritis is unknown, autoimmunity plays a pivotal role in its chronicity and progression.